The invention relates to surgical drill assemblies useful for penetrating bone.
Many surgical techniques require the perforation or drilling of bone. Cranial surgery, in particular, requires control over the cutting depth of a drill so that drilling takes place only through bone and not through the delicate dura underlying the bone. During surgery that requires penetration of the skull it is critical that drill rotation cease once the skull is effectively perforated, and before any damage is done to underlying dura.
There exist cranial perforators that permit drill bit rotation only when the drill bit is subjected to an axial load of a desired magnitude. Once the load is removed, or falls below a predetermined threshold, rotation of the drill ceases. Such devices that utilize a clutch mechanism which enables a driver to be engaged only upon sufficient axial load are disclosed in U.S. Pat. Nos. 2,842,131; 4,362,161; 4,319,577; 4,884,571; and 4,699,550.
Many existing surgical drill constructions utilize reusable drill bits and drill assemblies. After use, it is necessary to disassemble the drill, sterilize the drill components, and reassemble the drill before a subsequent use. Disassembly and reassembly is undesirable because it is time consuming, labor intensive, and because there always exists the possibility that reassembly will not be performed correctly. Improper reassembly of such a drill can lead to drill failure and consequently to patient injury or death. There is thus a need for economical and effective disposable surgical drill assemblies. It would also be advantageous to provide reusable surgical drill assemblies that can be rapidly and effectively disassembled and reassembled.
It is thus an object of the invention to provide a construction for a bone drill assembly that efficiently and effectively disables drill bit rotation when the drill bit is no longer subjected to a sufficient axial load. A further object is to provide such a drill assembly that is disposable. Another object is to provide a reusable drill that is easily disassembled and reassembled. It is also an object to provide a reusable drill that does not require disassembly of components before sterilization. These and other objects, features and advantages of the present invention will become more apparent from the following description.